Registering middleware in Laravel - Step-by-Step Execution

Concept Flow - Registering middleware

Create Middleware Class

↓

Add Middleware to Kernel

↓

Assign Middleware to Route or Group

↓

Request Hits Route

↓

Middleware Executes

↓

Request Proceeds or Blocked

Middleware is created, registered in the kernel, assigned to routes, then runs on requests to control access or modify requests.

Execution Sample

Laravel

<?php
// In app/Http/Kernel.php
protected $routeMiddleware = [
    'auth' => \App\Http\Middleware\Authenticate::class,
];

This code registers the 'auth' middleware by linking its name to the middleware class in the Kernel.

Execution Table

Step	Action	Details	Result
1	Create Middleware Class	Generate middleware file with handle method	Middleware class ready
2	Register Middleware	Add middleware to $routeMiddleware in Kernel.php	'auth' key linked to Authenticate class
3	Assign Middleware	Use 'auth' in route or group middleware	Routes protected by auth middleware
4	Request Received	User sends request to protected route	Request enters middleware pipeline
5	Middleware Executes	Authenticate::handle checks user auth	Request allowed or redirected
6	Request Proceeds	If authenticated, request continues to controller	Controller processes request
7	Request Blocked	If not authenticated, middleware redirects	User sent to login page

💡 Execution stops when request is either allowed to proceed or redirected by middleware.

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 5	Final
$routeMiddleware['auth']	undefined	\App\Http\Middleware\Authenticate::class	\App\Http\Middleware\Authenticate::class	Middleware instance	Middleware allows or blocks request
Request Status	New request	New request	Assigned to auth middleware	Checked authentication	Allowed or redirected

Key Moments - 3 Insights

Why do we add middleware to the Kernel before using it in routes?

Middleware must be registered in the Kernel's $routeMiddleware array so Laravel knows what class to run when the middleware name is used in routes. See execution_table step 2.

What happens if the middleware blocks the request?

If the middleware detects the user is not authenticated, it redirects the request (step 7), stopping it from reaching the controller. This prevents unauthorized access.

Can middleware be assigned to multiple routes?

Yes, once registered, the middleware name can be used on any route or group to protect multiple routes easily (step 3).

Visual Quiz - 3 Questions

Look at the execution_table, what is the result after step 2?

A Middleware redirects user

B 'auth' key linked to Authenticate class

C Request proceeds to controller

D Middleware class deleted

💡 Hint

Check the 'Result' column for step 2 in the execution_table.

At which step does the middleware check if the user is authenticated?

A Step 3

B Step 7

C Step 5

D Step 1

💡 Hint

Look for 'Authenticate::handle checks user auth' in the 'Details' column.

If middleware is not registered in the Kernel, what happens when used in a route?

A Laravel throws an error because it can't find the middleware class

B Middleware runs normally

C Request is always allowed

D Request is always blocked

💡 Hint

Think about the importance of step 2 in the execution_table.

Concept Snapshot

Register middleware by:
1. Creating middleware class with handle method.
2. Adding it to $routeMiddleware in app/Http/Kernel.php.
3. Using middleware name in routes or groups.
Middleware runs on requests to allow or block access.

Full Transcript

Registering middleware in Laravel involves creating a middleware class that contains logic to run on HTTP requests. This class is then registered in the app/Http/Kernel.php file inside the $routeMiddleware array, linking a short name like 'auth' to the middleware class. After registration, this middleware name can be assigned to routes or route groups to protect them. When a request hits a route with middleware, Laravel runs the middleware's handle method. The middleware can check conditions like user authentication and decide to allow the request to continue to the controller or redirect the user elsewhere. This process ensures controlled access and request modification in Laravel applications.